Taiho Oncology and Taiho Pharmaceutical Announce Positive Topline Results in Phase 3 AZTOUND Trial Evaluating Oral Azacitidine and Cedazuridine in Myelodysplastic Syndromes or Chronic Myelomonocytic Leukemia

PRINCETON, N.J. & TOKYO--(BUSINESS WIRE)--Taiho Oncology, Inc., and Taiho Pharmaceutical Co., Ltd., today announced positive topline results from the Phase 3 AZTOUND trial evaluating pharmacokinetic (PK) exposure, safety and efficacy of an orally available azacitidine and cedazuridine (ASTX030) in patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). The study met its primary endpoint of total cycle area under the curve (AUC) from 0 to 24 hours (AUC0-24) exposures, measured as the ratio of azacitidine total cycle AUC0-24 exposures following oral azacitidine and cedazuridine compared with subcutaneous azacitidine. The safety profile was consistent with parenteral azacitidine.

These results from AZTOUND will be submitted for presentation at an international medical conference. Based on these results, Taiho Oncology intends to submit a New Drug Application to the U.S. Food and Drug Administration (FDA) seeking approval of azacitidine and cedazuridine as an oral treatment regimen for adults with MDS or CMML.

“The positive topline results of the Phase 3 AZTOUND trial support the potential of an all-oral regimen of azacitidine and cedazuridine to meet the treatment needs of patients with MDS and CMML without the time and treatment burden associated with parenteral therapies,” said Harold Keer, MD, PhD, Chief Medical Officer, Taiho Oncology. “We look forward to pursuing regulatory approval of oral azacitidine and cedazuridine to potentially bring this treatment option to patients.”

“We believe the positive topline results of the AZTOUND Phase 3 trial mark a key milestone in our collective efforts to develop a portfolio of novel treatments that improve clinical outcomes and quality of life for people with hematological malignancies," said Fabio Benedetti, MD, Global Chief Medical Officer, Taiho Pharmaceutical. "We are grateful to the patients, caregivers and investigators participating in the AZTOUND trial and remain committed to advancing azacitidine and cedazuridine for patients with MDS and CMML."

About the AZTOUND Trial

Phase 3 of the AZTOUND trial is a randomized open-label crossover study that enrolled 88 adults with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). The primary objective was to assess total cycle area under the curve (AUC) from 0 to 24 hours (AUC0-24) exposures, measured as the ratio of azacitidine total cycle AUC0-24 exposures after oral azacitidine and cedazuridine over subcutaneous azacitidine.

About Oral Azacitidine and Cedazuridine

Azacitidine and cedazuridine (ASTX030) is an oral combination of azacitidine, a DNA methyltransferase inhibitor, and cedazuridine, a cytidine deaminase inhibitor added to help azacitidine stay active in the body without being degraded. Azacitidine and cedazuridine (ASTX030) is investigational and has not been approved by any health authority. Azacitidine and cedazuridine is being developed by Taiho Oncology, Inc. and its parent company, Taiho Pharmaceutical Co., Ltd.

About Myelodysplastic Syndromes (MDS) and Chronic Myelomonocytic Leukemia (CMML)

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic stem cell disorders. Each year, there are approximately 10,000 to 15,000 new cases in the U.S., though the disease is believed to be underdiagnosed.^1,2,3 Approximately one-third of these cases may progress to acute myeloid leukemia.^4,5 Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic malignancy characterized by accumulation of abnormal monocytes in the bone marrow and in blood. Approximately 2,000 new cases of CMML are diagnosed annually in the U.S. ^6,7 Between 15% and 30% of CMML cases may progress to acute myeloid leukemia.⁸

About Taiho Oncology, Inc.

The mission of Taiho Oncology, Inc. is to improve the lives of patients with cancer, their families and their caregivers. The company specializes in the development and commercialization of orally administered anti-cancer agents for various tumor types. Taiho Oncology has a robust pipeline of small-molecule clinical candidates targeting solid-tumor and hematological malignancies, with additional candidates in pre-clinical development. Taiho Oncology is a subsidiary of Taiho Pharmaceutical Co., Ltd. which is part of Otsuka Holdings Co., Ltd. Taiho Oncology is headquartered in Princeton, New Jersey and oversees its parent company’s European and Canadian operations, which are located in Baar, Switzerland and Oakville, Ontario, Canada.

For more information, visit https://www.taihooncology.com/, and follow us on LinkedIn and X.

Taiho Oncology and the Taiho Oncology logo are registered trademarks of Taiho Pharmaceutical Co., Ltd.

About Taiho Pharmaceutical Co., Ltd. (Japan)

Taiho Pharmaceutical, a subsidiary of Otsuka Holdings Co., Ltd. (https://www.otsuka.com/en/), is an R&D-driven specialty pharma focusing on the fields of oncology and immune-related diseases. Its corporate philosophy takes the form of a pledge: “We strive to improve human health and contribute to a society enriched by smiles.” In the field of oncology, in particular, Taiho Pharmaceutical is known as a leading company in Japan for developing innovative medicines for the treatment of cancer, a reputation that is rapidly expanding through their extensive global R&D efforts. In areas other than oncology, as well, the company creates and markets quality products that effectively treat medical conditions and can help improve people’s quality of life. Always putting customers first, Taiho Pharmaceutical also aims to offer consumer healthcare products that support people’s efforts to lead fulfilling and rewarding lives. For more information about Taiho Pharmaceutical, please visit https://www.taiho.co.jp/en.

References

1. American Cancer Society. Key Statistics for Myelodysplastic Syndromes (MDS). Accessed August 9, 2026. https://www.cancer.org/cancer/types/myelodysplastic-syndrome/about/key-statistics.html
2. Leukemia & Lymphoma Society. Facts and Statistics Overview. 2023. Available from: https://www.lls.org/facts-and-statistics/facts-and-statistics-overview. Last accessed: September 2026
3. Gorak EJ, Otterstatter M, Baghdadi TA, et al. Discordant pathologic diagnoses of myelodysplastic neoplasms and their implications for registries and therapies. Blood Adv. 2023;7(20):6120-6129. https://pubmed.ncbi.nlm.nih.gov/37552083/.
4. Volpe VO, Garcia-Manero G, Komrokji RS. SOHO State of the Art & Next Questions: Myelodysplastic Syndromes: A New Decade. Clinical Lymphoma Myeloma and Leukemia. 2022;22(1):1-16. https://doi.org/10.1016/j.clml.2021.07.031.
5. Dan C, Chi J, and Wang L (2015). Molecular mechanisms of the progression of myelodysplastic syndrome to secondary acute myeloid leukaemia and implication for therapy. Annals of Medicine, 2015;47(3):209–217. https://doi.org/10.3109/07853890.2015.1009156
6. Biology Insights. How Rare Is Chronic Myelomonocytic Leukemia (CMML)? December 2025. Available from: https://biologyinsights.com/how-rare-is-chronic-myelomonocytic-leukemia-cmml/. Last accessed: September 2026.
7. Recent Trends in SEER Age-Adjusted Incidence Rates, 2001-2023. 2026 Apr 22. [updated: 2026 Jun 22]. Available from: https://seer.cancer.gov/statistics-network/explorer/. Last accessed: September 2026.
8. American Cancer Society. Key Statistics About Chronic Myelomonocytic Leukemia (CMML). Revised March 7, 2025. Accessed August 26, 2025. https://www.cancer.org/cancer/chronic-myelomonocytic-leukemia/about/key-statistics.html.